Proof: Addi to Zero
Let's prove the following theorem:
if the following are true:
- instruction #i is
addi dst=dst src=0 imm=imm - the PC at time t = i
then value of cell dst at time (t + 1) = imm
Instructions
| Memory Cells |
|---|
| Program Counter | Time |
|---|---|
| 0 | 0 |
LW Computer Simulator
Proof:
Given
| 1 | instruction #i is addi dst=dst src=0 imm=imm |
|---|---|
| 2 | the PC at time t = i |
| # | Claim | Reason |
|---|---|---|
| 1 | value of cell dst at time (t + 1) = (value of cell 0 at time t) + imm | if instruction #i is addi dst=dst src=0 imm=imm and the PC at time t = i, then value of cell dst at time (t + 1) = (value of cell 0 at time t) + imm |
| 2 | value of cell 0 at time t = 0 | value of cell 0 at time t = 0 |
| 3 | value of cell dst at time (t + 1) = 0 + imm | if value of cell dst at time (t + 1) = (value of cell 0 at time t) + imm and value of cell 0 at time t = 0, then value of cell dst at time (t + 1) = 0 + imm |
| 4 | 0 + imm = imm | 0 + imm = imm |
| 5 | value of cell dst at time (t + 1) = imm | if value of cell dst at time (t + 1) = 0 + imm and 0 + imm = imm, then value of cell dst at time (t + 1) = imm |
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